The present invention relates to a non-contact pick-up device, and especially to a pick-up device which may be used in the manufacturing process of semiconductor for clamping a wafer.
In the manufacturing process, often, it is necessary to clamp a manufacturing material for performing necessary processes. For example, in the front stage of the manufacturing process of a semiconductor wafer, A plasma platform is used in etching, deposition, and cleaning. The use of plasma platform is important and widely used in the front stage of the manufacturing process of the semiconductor wafer. In the plasma platform, a wafer is placed in a wafer clipper, while the pick-up device is placed between the wafer and the wafer clipper for retaining the wafer so that the wafer is steadily fixed. In general, the pick-up device is classified into mechanical clamping devices and electrostatic clamping device.
A prior art clamping device disclosed in U.S. Pat. No. 4,692,836 is illustrated in FIG. 1, wherein the electrodes of the electrostatic clamping device has an absorbing disk 2 with a thickness a placed on a supporting frame 1. A wafer 3 is placed on the absorbing disk 2. b is the curvature due to the non-uniformity of the electrostatic force, however, this is not the key point of the present invention, and thus the details will not described herein. The electrodes 4 are connected to the absorbing disk 2 and a substrate. A DC voltage is applied to the electrodes. However, in this design, the conductive wire is necessary to be connected to the electrostatic clamping device and the wafer, and thus as a wafer is updated, the conductive wire must be connected further. Moreover, due to a voltage applying to the wafer, the electric property of the wafer is changed.
Supports for disk-shaped articles by using mechanical clamping device have also been known from U.S. Pat. Nos. 4,903,717 and 5,492,566. In thus conventional support, these supports do not exhibit any propping means in the surface facing the disk-shaped article so that the latter is returned in the support exclusively by Bernoulli""s on a gas cushion forming between the disk-shaped article and the support. In that patent, a mechanical clamping device includes a lower cup-shaped article 7 and an upper cup-shaped article 8. The lower cup-shaped article 7 is an annular air channel 101 and is formed as a channel with the upper cup-shaped article 8. Moreover, a disc-shaped article 10 is placed above the upper cup-shaped article 8. The air flows into an annular air channel 101 from the channel 6. Since air flows through the channel, according to Bernoulli concept, the air will generate a pressure difference on the surface of the disc-shaped article 10. However, the pressure difference from a flowing air will be smaller than atmosphere pressure applied on another surface of the disc-shaped article 10 and thus, the atmosphere pressure applies a pressure on the disc-shaped article 10 to clamp the disc-shaped article 10 to the cup-shaped article 8.
Such a prior art design has still defects, for example, air jets out from a single outlet. Since the mechanical errors (for example, the error of air channel 101 generated in the manufacturing process; the assembly of the components; the wearing due to operation through a long time period), the airflow becomes non-uniform in the airflow channel and thus, the clamping force of the upper disk 8 to the disc-shaped article 10 is not uniform. However, for the precision elements, slight errors will induce bad products. For example, in the manufacturing process of a wafer (i.e., the disk body 100 is a wafer), since the progress of semiconductor technology, a manufacturing process of 0.13 micrometer is developed. In such a fine manufacturing process, a slight error will induce a difficulty in precision control of the products.
Accordingly, the primary object of the present invention is to provide a non-contact type thin plate clamping device, wherein the shifting and parallel levels of the disc-shaped article are detectable by a photodetector. And then by a self detecting/controlling module, the amount of jetting air can be adjusted so as to correct the shifting and parallel levels.
Another object of the present invention is to provide a non-contact type thin plate clamping device, wherein in the present invention, by the number of the nozzles and a control module, the shifting and parallel levels of the disc-shaped article 10 can be well controlled.
A further object of the present invention is to provide a non-contact type thin plate clamping device, wherein since air jets out from the nozzles, the air generating in the manufacturing process will not flow into the air channel so as to destroy the whole mechanism.
The other object of the present invention is to provide a non-contact type thin plate clamping device, wherein since the air jets out from the nozzles, the air generating in the manufacturing process will not contact the surfaces of the disk body (such as the surfaces of a wafer), and thus, the chemical property of the back side of the wafer will be retained in the original condition.
To achieve above objects, the present invention is to provide a non-contact type thin plate clamping device that utilized the Bernoulli principle to provide the pick-up force. The non-contact pick-up device mainly includes a disk, and a plurality of air nozzles above the disk. Each nozzle having an air channel; an upper end of the channel is tilt outwards. Therefore, as a disc-shaped article is placed on the disk; the air jets out from the nozzles, due to Bernoulli theory, a periphery of the disc-shaped article has pressure difference. Thus, due to the action of atmosphere pressure, the disc- shaped article will be clamped. The pick-up device may be used in the manufacturing process of semiconductor for clamping a wafer.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.